Properties and Characterization of Temperature-Responsive Asphalt by Using Thermochromic Powder

Abstract Asphalt pavement absorbs solar energy efficiently during the summer and loses heat rapidly during the winter because of its black color, which leads to rutting and cracking distresses. The thermochromic powders were used in this study to reverse the process with its ability to dynamically change color (albedo in essence) subject to temperature variations. Three types of thermochromic powders (the red, blue, and black ones) were applied to base asphalt at the contents of 3, 6, and 10 % to prepare the thermochromic asphalt. The gel permeation chromatography, Fourier transform infrared spectroscopy, physical, rheological, and thermodynamic properties of base and thermochromic asphalt binders were investigated via laboratory tests. The temperature-regulating function of thermochromic asphalt binders was examined in the field. Throughout the study, it is revealed that with the addition of thermochromic powders, the penetration and creep rate of asphalt binder decreased, whereas the softening point, viscosity, rutting parameter, and stiffness increased. When the powder content is 3 %, the intermolecular force within asphalt is enhanced; therefore, the consistency of asphalt is improved while the flow ability is weakened. While the content continues to raise, the thermochromic powder is prone to produce particle agglomeration. Thermochromic asphalt has a much higher specific heat capacity and latent heat than base asphalt, reflecting the principle to regulate temperature. Temperature reduction of 4°C∼5°C was observed for thermochromic asphalt binders compared with base asphalt in the field test. Considering the performance balance and economics, the content of thermochromic powders was recommended to be 5∼6 %. After adding thermochromic powders, the surface temperature of asphalt pavement can be effectively reduced during the summer and the road temperature during the winter will remain adequate to prevent cracking or icing.